1. Field of the Invention
The invention relates to a flat ring packing to be placed between two flanges and comprising two packing layers of packing material and an intermediate ring of metal which is disposed between the two packing layers and has a common central longitudinal axis therewith.
2. Background Art
Flat ring packings of the generic type are used for instance in pharmaceutical and foodstuff industry. In this case, a prerequisite resides in that the flanged joints do not exhibit any so-called wake spaces, i.e. spaces of poor flow. This is why the flat ring packings on the one hand and the pipes and apparatuses which the flanges are mounted on are to have identical inside diameters.
In known flat ring packings provision is made for an intermediate ring which is inserted into a sleeve of packing material. This one-piece sleeve forms packing layers which are joined to each other undivided in the radially inner area. In this case, radial play and also axial play must be available between the intermediate ring and the sleeve which comprises the packing layers in order that any tearing of buckling of this sleeve during assembly be avoided. It is difficult to center the sleeve of packing material and the intermediate ring of metal between the to-be-connected flanges in such a way that no wake spaces will form relative to the pipes.